Comparative study of copper films prepared by ionized metal plasma sputtering and chemical vapor deposition in the Cu/TaN/SiO2/Si multilayer structure

This work investigated the properties of ionized metal plasma (IMP) deposit ed copper (Cu) and chemical vapor deposited (CVD) Cu on IMP-TaN (tantalum n itride) diffusion barrier in the Cu(200 nm)/TaN(30 nm)/SiO2(250 nm)/Si mult i-layer structure. The IMP-Cu film deposited on IMP-TaN had a preferred ori entation (220) with a grain size of around 30 nm and roughness (RMS) of sim ilar to1.391 nm, while the CVD-Cu had a (111) preferred orientation with a grain size around 170 nm and roughness (RMS) of similar to 15.416 nm as det ermined by atomic force microscopy (AFM) and x-ray diffraction (XRD) analys es. Thermal stability study of the structures was also performed by sheet r esistance measurements, scanning electron microscopy (SEM), XRD and Rutherf ord backscattering spectroscopy (RBS). These results revealed that IMP-Cu o n IMP-TaN has higher thermal stability, less intermixing and/or agglomerati on than CVD-Cu on IMP-TaN at the same annealing temperatures. The higher th ermal stability of IMP-Cu than CVD-Cu can be accounted by their difference in microstructure. The failure mechanisms of IMP-Cu and CVD-Cu in multiplay er structure were also discussed. (C) 2001 Kluwer Academic Publishers.